Deep bar effects produced by PWM power supplies in induction machines: Application to rotor parameters determination

Generally, the induction motors are designed for supplying conditions from an energetic source at which the supplying voltage represents a sinusoidal wave. If the machine is supplied by voltage inverters, in the wave of the voltage entering the motor, the superior time harmonics, of the order v = jm f ± k, j = 1, 2, ...; kϵZ, occur. They are even, providing j is odd, and odd, providing j is even. The presence of the time harmonics in the supplying voltage determines, among others, an intensification of the skin effect at the start of the motor, comparing to the situation of sinusoidal supplying. The present study is focused on the skin effect which occurs in the deep bars of the rotors of the three-phase induction motors, where they are supplied by voltage-source-invertors. In this work is being treated the problem of the theoretic determination of the equivalent modification factors of the rotor parameters, while the cage induction motors are being supplied by inverters. The determination of these two factors is being globally made.